In the art of etching printed circuit boards, the boards are generally masked, to prevent etching of copper portions thereof, with unmasked portions of the board having copper portions etched by an acid, such as ferric chloride or the like. For purposes of this invention, such acid may be referred to as "treatment fluid," and is usually in the liquid state. However, the treatment fluid can be any treatment material in a fluid state. Such acid has in the past been applied and thereafter rinsed from the board following an etching operation, thereby contaminating the rinse water, requiring regular discharge of the rinse water, carrying the acid to sewage, and eventually to waterways and the like and thereby contaminating the environment. Furthermore, the etchant or treatment fluid is lost, and not available for re-use, unless an expensive reclamation process is utilized. In any event, prior art techniques have involved substantial expense, either by necessitating the loss of the etchant after use, or necessitating the utilization of expensive reclamation equipment.
Furthermore, in the art of printed circuit board manufacture, the mask or "resist," applied to the printed circuit boards must be removed in a subsequent operation. Such removal is generally effected by the use of a solvent, generally of the alkaline type, for removal of resist of the soluble silkscreen ink or photoresist type, when the resist is of the acid type. Accordingly, the term "treatment fluid" is intended also to encompass solvents and alkaline solutions.
As in the past, following application of etchant to printed circuit boards, water sprays are generally used to remove solvent that remains on the boards following a solvent stripping operation, such water sprays also contaminating sewage, waterways and the like, and furthermore requiring either loss of the solvent or other treatment fluid, or else requiring expensive equipment for reclamation of the same.